you believe in data - so do I! ALL the data I have been able to glean about roof-mounted turbine performance has been really grim! (As in the top of this thread) - this is actually the best performance I've seen by far!
If you had satisfactory verified performance data, you'd print it, and shut up all your critics - as I have seen none, I presume it doesn't exist!
I still maintain that a roof-mounted turbine on the average home, in the average town, can never get anywhere near generating the much-vaunted claim of 30% saving!
By the way, what happened to the Warwickwindtrials? - seems to have come to a grinding halt some months ago - three months of data, confirming my suspicions (about 3mph average wind), then zilch for months.......I wonder why?

http://solarwind.org.uk - a small company in Sussex sourcing, supplying, and fitting alternative energy products.
Amateurs encouraged - very keen prices and friendly helpful service!